This invention relates to a controlling system for a sewing machine, more particularly, to that having a work feeding means and a feed reversing means. This invention is especially useful for a non-ravel seaming in the beginning and finishing stage of sewing operation, and concerned particularly with the control of the non-ravel seaming device.
Heretofore many types of sewing machines have been provided, being capable of performing a non-ravel seaming at the beginning and/or finishing stage of the sewing operation. In a typical machine of those a non-ravel seaming process is as follows: (1) a seaming of forward feeding is carried out first for a certain period of time followed by that of opposite direction for another certain period of time; then (2) an ordinary seaming process of desired length is proceeded; and afterwards (3) a seaming of backward feeding for a certain period of time and again that in the opposite direction for another certain period of time are carried out as a finish step. These starting and finishing non-ravel seamings are to be done, of course, at the opposite ends of the ordinary seaming part in the middle in order to prevent the seaming from being raveled or unseamed.
The above-mentioned non-ravel seaming is, however, executed in a style wherein the forward and backward or reverse stitches are made overlappingly on the ordinary sewed stitches at the opposite end portions thereof.
This way of stitching is not enough durable under a rough use condition; non-ravel stitches applied on a thick cloth, material, or a dress are apt to be raveled or worn when the material is handled in a harsh way.